Late last year the owners of a 3.44-hect-are plot of land near the National Museum of Marine Biology and Aquarium in Houwan Village, Checheng Township, Pingtung County, cleared weeds and trash from the land by burning. The fire killed large numbers of land crabs that were living there, and the sight of their charred corpses scattered across the burnt land infuriated environmental groups. But the incident also aroused public curiosity in the ecology of these creatures.

Taiwan was once a haven for land crabs. However, with the degradation of the environment, these lovable crawlers are facing extinction. Pictured here is an egg-bearing Cardisoma hirtipes.

Inhospitable environs

Liu Hung-chang, assistant professor in the Department of Ecology at Providence University, and one of Taiwan's few experts on crab species, says that the term "land crab" may be applied to those crab species that are able to survive in wetlands or on land. A stricter definition of "land crab" would narrow it down to only around 20 species in the family Gecarcinidae, a tiny proportion of the 7000 crab species worldwide. Six of these species are to be found in Taiwan, including Cardisoma carnifex, Cardisoma hirtipes, Cardisoma rotundum, Gecarcoidea lalandii, Epigrapsus notatus, and Epigrapsus politus.

The number of land crabs that perished in the fire was conservatively numbered at over 5,000. Amidst mounting pressure, Li Teng-chih, assistant director of the Kenting National Park Administration Office, stressed that the crabs had moved to that area as a result of the habitat destruction caused by the development of the National Museum of Marine Biology and Aquarium. This parcel of land had been zoned for tourism, and the developer that had initiated the burning needed only the permission of the Pingtung County government. Only in the case of subsequent development planning would the developer need to seek permission from the national park. The park administration has already fined the developer over the death of the crabs, and has also required that the developer come up with a planning process that would provide a hospitable environment for the crabs.

Land crab paradise

According to the Research Center for Biodiversity at the Academia Sinica and foreign experts, Kenting National Park's Banana Bay contains multiple species of land crab, making it the most diverse known habitat in the world for the creatures.

The period from May to November each year, when tour buses are arriving in droves to the national park, also marks the time when female land crabs must make their way from the coastal forests and over the roads to lay their eggs on the shore. However, with the development of Provincial Highway 26 into a four-lane highway slicing through the coastal forest the "breeding corridor" for the land crabs has been obstructed by concrete ditches, the asphalt road, concrete barriers, and chain-link fences. These developments threaten the very survival of the crabs.

"The Pingtung-Oluanpi Highway at Banana Bay is wide and straight, so drivers on this stretch often speed up without realizing it. If the land crabs travel over the highway on a congested weekend evening to lay their eggs, the next morning one sees piles of crushed crabs," says Liu Hung-chang. Large groups of land crabs are also a conspicuous target for crab-hunters. Liu estimates that of every 100 crabs that die in Kenting, around ten are run over by automobiles, while most of the rest are caught for bait or consumption.

Yielding the road to land crabs

In 2003, to protect female land crabs as they cross the roads to lay their eggs, the Kenting National Park Administration initiated an activity designed to escort land crabs across the roads. This event takes place right before and after the full moon during the summer months, and calls on the public to join in efforts to protect the mother land crabs. Aside from controlling traffic on the highway during these times, the police put up warning signs at Banana Bay, where many land crabs perish. The signs alert drivers to slow down, especially during the summer full moon, and to yield the right of way to the crabs.

Li Teng-chih points out that after a few years of such public education, the sight of people hawking crabs captured in cloth bags, for NT$50 each, has been replaced by the sight of local environmental tourism entrepreneurs guiding visitors along the highways to observe land crabs breeding.

The Kenting National Park has commissioned the creation of "habitat corridors" to be dug under stretches of highway where land crabs most often perish. The habitat corridors are to be planned by Hsu Hai-lung, professor at the National Pingtgung University Institute of Wildlife Conservation, and will stretch from Chuanfan Rock to Banana Bay. However, environmental groups question the effectiveness of the project, raising the possibility that the crabs will become easy game for hunters. The project has thus been stalled.

Moreover, concrete barriers erected along the coastal forests have blocked the paths of the female land crabs, and crabs that go down into drainage ditches are often unable to get back out. Li has thus proposed a simpler solution: "We just have to cover over the drainage ditches and leave a gap in the roadside barriers every few meters. If we do this, the crabs can pass over quickly to their breeding grounds and will not remain on the road where they risk being run over."

The Kenting National Park also exhorts the public not to wilfully capture land crabs, but to abide by Article 13 of the National Park Law: "No living thing may be taken out of the national parks." Anyone caught capturing land crabs will be fined up to NT$15,000 and prosecuted for the theft of national property. Li exhorts, "The land crabs are one of the Hengchun Peninsula's treasures. We have to cherish them and not wait to lament their disappearance when it's too late.